The FC30-BT Frequency Counter covers 500 kHz to 50 MHz with 100 Hz resolution. The six bright LEDs are blue. There is three level dimmer switch on the front panel. Sensitivity is 0.1-1 V max. Stability is ± 1 PPM. Requires 12 VDC. The rear panel has an RCA phono jack for RF input. Additionally, there is prewired cable that is compatible with certain CB radios for easy one-step plug-in operation.